Gas heated appliance



Aug. 6, 1935. v w m ET AL I 2,010,762

GAS HEATED APPLIANCE Fil ed June 28, 1952 2 Sheets-Sheet 1 Aug. 6, 1935. a. HEGWEIN ET AL GAS HEATED APPLIANCE Filed June 28, 1952 2 Sheets-Sheet 2 i 1 11 33 16 16 Z5 25 2s 24 26\ I a 1 J v 3 27' so 29 2 1 f 32 9 25 -Patented Aug- 6, 1935 2,010,762

UNITED STATES PATENT OFFICE GAS HEATED APPLIANCE Georg Hegwein, Curt Steinhardt, and Friedrich Wilhelm Stockmeyer, Stuttgart, Germany, assignors to Junkers & 00. G. m. b. 11., Dessau, Germany Application June 28, 1932, Serial No. 619,770

In Germany July 18, 1931 7 Claims. (Cl. 158-117.1)

The present invention relates to gas heated thermostatic valve closes and thereby also efappliances. fects the instantaneous closing of the main gas In gas-heated appliances (water heaters and valve. stoves for bath-rooms and other rooms) which In the drawings, three examples of construcare connected to a chimney, the danger always tion of the invention are diagrammatically 5 exists that the waste gases may be held back shown, in which:-

in the burner chamber by an unfavourable wind, Figure 1 is a liquid heater with the known and incomplete combustion takes place, so that back-draught safety device.

carbon monoxide is formed. Such appliances Figures 2 and 3 show the same type of heater J have therefore been provided on the waste gas with a thermostat installed in the back-draught outlet pipe or conduit with back-draught safety opening in accordance with the present invendevices in the form of draught-intercepting tion, these views showing the positions during openings, which allow the dammed-back waste normal draught and back-draught respectively. gases to escape from the appliance, so that they Figures 4-6 present a second example of con- 5 do not affect the combustion. By such safety struction of the invention and show a liquid devices defective combustion is indeed preheater with a guardian flame safety device in vented, but they do not afford any security differing conditions as to the flame, before, duragainst fatal accidents; on the contrary, the ing and after the back-draught. waste gases emerging into the ,room are very Figure 7 presents a third example of construc- 3 dangerous, since they containgreat quantities of tion of the invention and shows a further form '20 poisonous gases which are dangerous to respiraof construction of the guardian flame safety tion, so that even a short stay in rooms filled device. with the. back-draught gases may cause insensi- Referring first to the prior art or known arbility and, finally, death, The danger is, of rangement as illustrated in Fig. 1, above the course, particularly great in bath-rooms, which combustion chamber ll of a heat-exchange ar generally have only a small air capacity. rangement II) a draught-intercepting hood l2 The present invention removes the danger of with waste gas Out P p '3 is arranged; A back-draught persisting for any substantial deflecting cone l4 diverts the waste gases flowlength of. time by providing safety devices in the ing' back from the waste gas outlet pipe later- 5 back-draught passages actuated by the backally into the draught-intercepting passages l5, so draught gases to out oi the supply of gas to the that they cannot reach the heating chamber ll. burners (at least to the main burner). By the The main burner I6 is controlled by the main interruption of the-supply of gas the b rner gas valve I1 and the pilot flame pipe l9 branches flames are extinguished, so that the further dis-. off the gas p is in advance of the main Valve- 5 charge of waste gases into the room ceases. In In the right h f of F g. 1 the usual P Of the this way the danger of the filling of a mom waste gases without back-draught is shown. with poisonous gases is also removed. The left a 1 shows the P Of the The safety devices provided in the path of waste gases when a back-draught occurs, and t r ht gases may be of the most it will be at once seen that the returning waste 0 varied kind so long as they are responsive to the gases p y enter the room in Which the 40.

back-draught gases. Thus, a thermostat can heated app an e'is fitted. If the wind pe ts, be arranged in the path of the back-draught it may happen that the apartment (bathroom.

, gases which is actuated by the heat of the backc e tth like) becomes u y fi d t draught gases, and, for example, effects the r waste gases so that the persons therein are in 5 lease of a self-closing main gas-valve, so that it danger of their lives. interrupts the main gas current. Preferably the In Figs. 2 and 3 the same liquid ea is shown back-draught gases are conducted in or through p v d w a safety device a rdin to the the combustion chamber to a guardi flame present invention. This device consists of a-therwhich controls, by means of athermostatic valve, mostat, fo e p a lei-metallic p a, gas current which in turn controls the main which is arranged in the draught-intercepting gas valve pneumatically in known manner. As flue l5, and in the cold condition holds the valve soon as a return flow of waste gases takes place rod 2| of a main gas valve 22 which closes autoowing to back-draught in the outlet pipe, the matically under spring action and which is shown guardian flame is at once extinguished in the in the open position in Figure 2. If a backgases which are poor in oxygen, so that the draught occurs (Fig. 3), the hot waste gases flow l5 past the thermostat 26 and cause it to expand and release the valve rod 2!, so that the valve 22 closes and interrupts the supply of gas to the burner it. The burner flames are thus extinguished and the formation of waste gases ceases. The stove can only be brought into use again by opening the main valve 22 and igniting the gas at the-main burner, so that the user is warned and cannot be surprised by gas poisoning. If back-draught again takes place after the re-ignition of the burner, the safety device will again act after a short time, and the gas supply will again be cut off so that in any case a long continued return flow of waste gases into the room is avoided.

In Figures 4-6 a further liquid heater is shown which however possesses a back-draught safety device which becomes operative by the extinction of a guardian flame. Between the main burner l6 and the main gas-pipe 8 a diaphragm valve 23 is arranged, the diaphragm 24 of which contains a throttle opening 25 through which a weak current of controlling gas constantly flows from the high pressure side 26 of thediaphragm into the control chamber 21. From the control chamber 2'! a controlling gas-pipe 28 leads 'to the burner 29 of a guardian flame, which acts on a thermostat valve controlling the gas-pipe 28. In the example shown, the guardian flame burner 29 is itself formed as a safety burner by the burner casing 29 being closed by a thermostat disc 30 which contains a burner opening 3! and carries a valve plate 32. When the thermostat disc 33 is cold, it presses the valve plate 32 on its seat and thereby closes the outlet of the control pipe 28, so that the control gas collects in the control chamber 21 of the main valve and presses the diaphragm 24 against the main valve seat (Fig. 6) If however the thermostat disc 30 is heated by a flame, for example, the guardian flame, it curves and opens the valve 32, so that the pressure escapes from the control chamber 21 and opens the main gas valve (Fig. 4). This guardian flame, the burner of which may of course have a different construction, is so arranged that it lies in the path of the returning Waste gas when a back-draught occurs and is extinguished thereby. It could thus (like the thermostat 20 in Figs. 2 and 3) be arranged in the draught-intercepting passages Hi; In order however that it may be put out with certainty, it is preferably arranged in a chamber which the back-draught gases can completely fill so that the guardian flame lies in a waste gas sump. For this purpose, the draught-intercepting hood I2 is so extended. that it forms a casing 33 which extends down below the burner l6 and has a bottom 34 containing a fresh air opening 35. If now a backdraught occurs, the returning waste gases are conducted round the heat exchanger to the guardian flame chamber 36. On a back-draught, the chamber 36 is filled to such an extent with waste gases poor in oxygen that the guardian flame in the waste gas sump (Fig. 5) becomes extinguished. This has for its consequence that the thermostat disc 30 becomes cold and closes the control valve 32, so that the main valve 23 also closes and shuts off the gas supply to the burner 16 as shown in Fig. 6. In order to increase the action of the chamber 35, a non-return flap-valve 31 can be provided on the fresh air opening 35 which is held open by a counter-weight 38, a spring or the like, and is closed by the back-draught pressure.

from the guardian flame chamber 36, and has its own fresh air inlet 30. Only one opening ll in the wall 39 opposite the guardian flame allows the guardian flame to pass through to the main burner l6, so that it can be used at the same time as a pilot flame.

It is further to be noted that the deflecting cone 42 shown in Figs. 4-7 has the form of a cup directed towards the outlet pipe or flue 13, so that condensed water, soot and so forth cannot reach the heating chamber II or the burner l6.

What is claimed is:

1. A gas-heated appliance comprising a heat interchanger, a combustion chamber, a main gas burner therein, a flue leading from said combustion chamber, a return conduit for back-draught gases opening into said flue and means arranged in the path of the back-draught gases in said conduit and responsive to the flow thereof to automatically interrupt the supply of gas to said main gas burner.

2. A gas-heated appliance comprising a heat interchanger, a combustion chamber, a main gas burner therein, a flue leading from said combustion chamber, a return conduit for back-draught gases opening into said flue and thermostatic means arranged in the path of the back-draught gases in said .conduit and responsive to the flow thereof to automatically interrupt the supply of gas to said main gas burner.

3. A gas-heated appliance comprising a heat interchanger, a combustion chamber, a main gas burner therein, a flue leading from said combustion chamber, a return conduit for back-draught gases opening into said flue, means including a thermostat operable to interrupt the supply of gas to said main gas burner and a guardian burner positioned to heat said thermostat, said guardian burner being positioned in said conduit in the path of the back-draught gases and extinguishable thereby.

4. A gas-heated appliance comprising a heat interchanger, a combustion chamber, a main gas burner arranged in said combustion chamber, a main valve controlling the supply of gas to said main gas burner, a flue leading from said combustion chamber, a return conduit for backdraught gases opening into said flue, a sump arranged in said return conduit, and means responsive to the flow of back-draught gases in said conduit for controlling said main valve comprising means including a thermostat operable to close said main valve and thereby interrupt the supply of gas to said main gas burner on cooling of said thermostat and a guardian-burner positioned to heat said thermostat by its flame and arranged in said sump.

5. A gas-heated appliance comprising a heat interchanger, a combustion chamber, a main gas burner arranged in said combustion chamber, a main valve controlling the supply of gas to said main gas burner, a flue leading from said combustion chamber, a return conduit for backdraught gases opening into said flue, a sump arranged in said return conduit and having an opening communicating with said combustion chamber, and means responsive to the flow of back-draught gases in said conduit for controlling said main valve comprising means including a thermostat operable to close said main valve and thereby interrupt the supply of gas to said main gas burner on cooling of said thermostat and a guardian burner positioned to heat said thermostat by its flame and arranged in said sump adjacent the opening therein so that the flame of said guardian burner projects through said opening and serves as a pilot flame to said main gas burner.

6. A gas-heated appliance comprising a heat inter-changer, a combustion chamber, a main gas burner arranged in said combustion chamber, a main valve controlling the supply of gas to said main gas burner, a flue leading from said combustion chamber,v a return conduit for backdraught gases opening into said flue, a sump arranged in said return conduit, a flap valve in said sump controlling the supply of airthereto and closing under pressure of the back-draught gases, and means responsive to the flow of backdraught gases in said conduit for controlling said main valve comprising means including a thermostat operable to close said main valve and thereby interrupt the supply of gas to said main gas burner on cooling of said thermostat and a guardian burner positioned to heat said thermostat by its flame and arranged in said sump.

7. A gas-heated appliance comprising a heat interchanger, a combustion chamber, a main gas burner therein, a flue leading from said combustion chamber, a return conduit for back-draught gases opening into said flue, a deflector arranged in said flue to deflect back-draught gases into said return conduit and means arranged in the path of the back-draught gases in said conduit and responsive to the flow thereof to automatically interrupt the supply of gas to said main gas burner upon flow of back-draught gas.

GEORG HEGWEIN. CURT STEINHARDT. FRIEDRICH WILHELM STOCKMEYER. 

